During the past two years, field surveys, literature reviews, and analyses based on numerical models were conducted. The focus was on the flood inundation, characteristics of river network in the delta area, sea water intrusion, sedimentation and deforestation. During these filed trips, the research team made contact with administration bodies of the Mekong river, research institutes and Vietnamese universities as well. A lot of data were collected which forms the basis for further study.Two workshops were organized to discuss the issues of the Mekong river basin, particularly, the one held on January 1999 brought more than 30 participants. Three experts on Mekong river from abroad attended the meeting, and provided updated information related to the latest developments of the Mekong river basin. Through the meetings, different views were exchanged and better understanding were achieved. Under this reseach program, a mathematical model to calculate inundating flow for northern Mekong d
… Moreelta was developed. The output of the model is compared fairly well with the recorded flood data. Numerical simulations of flow and bed evolution around the junction between the Mekong river and the Bassac river were also performed. Tendencies of sediment deposition at the merging area were predicted. Besides, a distributed hydrological model was applied to the watershed of the Tonle Sap lake to assess its water balance budget. Also, experiments were done to study the mechanism of the sea water intrusion, as a result, several proposals were made for the prevention of saline wedge intrusion.In conclusion, a framework for sustainable development planning in the lower Mekong river basin has been formed which can serve not only academic purposes but also help enhance the efficacy of Japanese government overseas assistance towards sustainable development of the Mekong River Basin.本研究により、メコン河、バサック河およびデルタ内の水路・運河によって構成される河川網と河川網に囲まれた氾濫原(多くは農地)における洪水氾濫水の挙動を、一次元モデルおよび平面二次元モデルを組み合わせて解析するモデルを開発した、既往の氾濫と比較して少なくとも定性的には一致する結果が得られた。また、メコン河とトンレサプ河との合流領域における流れと河床変動の数値解析を行った。この領域の流れの再現と侵食・堆積傾向の予測を試みた。その結果、数条件下での流況と合流部での堆積傾向が再現された。また、トンレサプ湖の流域における土地利用のデータ整理ができ、水収支計算が行った。さらに、エアカーテンによる塩水楔の遡上阻止に関する実験が行った。塩水侵入阻止ための幾つかの工学的手法をを提案した。本研究によるメコンデルタ地域の開発の基礎資料を作成することができた。今後、この資料を基づいてさら詳しく分析を行い、メコン地域の河川に対する学問的な成果としてだけでなく、今後我が国の経済援助を行う際の重要の情報として役立てる。 Less